American preference for neutrality or political isolation (in order to remain aloof from Europe''s wars) and territorial expansion (two foreign-policy principles with roots in the colonial and early national periods) remained little changed. Americans also held to their equally old belief that their nation had a duty to serve as a model or inspiration to the world. Whether that national sense of mission is viewed religiously or secularly, Manifest Destiny gave it a new and more aggressive character. Its application reflected not only the old desire for territorial expansion but also the Monroe Doctrine''s commitment to keep European powers from extending their institutions or their colonies to the New World. Running throughout foreign policy issues, however, is the influence of the slavery issue.